Service tax query

Mr. Kamal as per the fact provided by you, you are not the employee of USA Co., infact you are providing your services to your USA based client on principal to principal basis. Indeed, you are exporting you service to your USA client.

The service which you are provididing to your client, i.e, "Promotion of Products or Services provided by client" is a service covered under the catagory "Business Auxiliary Service" (Section 65(19) of Finance Act, 1994) and you are liable tfor service tax if your aggregate receipts towards value of srvices renderd exceeds Rs.10 Lakhs during the year (assuming that you are an eligible SSI for the current year i.e, the value of services rendered by you does not exceeded Rs.10 Lakhs during the preeceeding F.Y.). 

Futher, you need to take registration within 30 days from the date, when your aggregate value of services rendred by you exceeded Rs.9 Lakhs by making an application in Form ST-1 to the Superintendent of Central Excise..

In case of erstwhile Business Auxiliary Service, commission agents were exempted from the purview of service tax.

In the present scenario also, you are receiving the money in convertible foreign exchange. It is an export of service and hence, not liable to service tax.

As per my view, your commission income is not taxable.